基于分段解算模型的线要素缓冲区生成算法

从线要素缓冲区构建的角度出发,通过挖掘线要素各线段(局部)缓冲区之间的空间几何关系,构建了线要素缓冲区分段解算模型。在此基础上提出了基于分段解算模型的线要素缓冲区生成算法,阐述了该算法的基本原理和实现步骤,并在VC++环境下对算法进行了验证。     

基于骨架线的Douglas-Peucker算法改进

针对Douglas-Pecuker算法中以垂直距离为化简指标的不足,提出了以骨架线为化简指标的改进算法.在对曲线凸凹顶点识别基础上,通过三角网的构建实现了凸点到基线的骨架线的提取,结合Douglas-Peucker算法的一般步骤,进行了曲线化简实验和方法的比较,验证了改进算法在保持线要素形态特征上的合理性.     

用数学形态学变换提取地性线的一种方法

地性线是非常重要的地形结构信息,应用领域十分广阔。采用单纯的矢量方法提取的地性线往往不连续,比较零碎。阐述了利用数学形态学的流域分割算法提取地性线的原理,介绍了基于等高线,采用矢量栅格混合算法提取地性线的具体步骤,最后,给出了结论,实验结果表明,采用本文提出的算法是可行的,提取的地性线有较好的连续性。     

基于滚动圆模型的线要素综合方法

针对当前滚动圆模型大多采用双向缓冲区模型进行构建,其在缓冲区构建过程中涉及了大量缓冲区叠置计算处理,算法较为复杂的不足,提出一种基于滚动圆模型的线要素综合方法。从滚动圆的定义出发,分析了利用滚动圆模型综合曲线时遇到的几种基本情形,计算并推导了相应的计算公式;最后通过实验验证了本文方法的有效性。     

闭合多边形旋转方向判定的更优方法

闭合多边形的旋转方向判定是GIS空间分析和算法中较重要的内容之一,由于现在算法较多,其算法的效率和精确度参差不一。对比分析了基于凸包的闭合多边形旋转算法、基于多边形面积计算的闭合多边形旋转算法和基于凹凸顶点判定方法的闭合多边形旋转算法,从算法设计复杂程度、算法效率等方面进行了详细阐述,指出了基于凹凸顶点判定方法是最简单最有效的一种判定方法。     

基于线框图的三维实体重构算法

通常情况下 Wire- frame(线框图 )不能唯一描述 3D object。本文给出 1种基于 Wire- frame的 3D object重构求解算法。该算法获得唯一解时 ,则表明 Wire- frame对应唯一的 3D object;多个解时 ,则给出所有的可行解     

高精度缓冲区边界相向逼近求交算法研究及实验

针对海洋划界等距离线/中间线方法中双方距离比例不为1∶1时的海洋划界存在的不足,探讨了基于欧氏平面的距离等比例线法及其后续研究存在的精度无法满足海洋划界的实际应用需求的问题,提出了基于地球椭球体解算距离等比例线的高精度缓冲区边界相向逼近求交算法,并阐述了该算法的基本原理和实现步骤,最后结合海洋划界实例,对该算法的有效性进行了验证。     

基于骨架的角毛藻显微图像特征提取

骨架是表征物体形状的1种有效形式。基于骨架对角毛藻细胞区域形状进行标识,提出1种基于竞争策略的骨架层次分解算法,该方法通过定义使与脊柱基元具有一致方向性的分支基元获胜跟踪的竞争策略,消除了骨架提取中不同分支的相互影响,保证分解后脊柱基元的完整性;针对角毛藻细胞具有的生物学特征,采用脊柱基元的弯曲度、角毛分支基元与脊柱基元的夹角作为角毛藻细胞的特征度量值,进一步建立了角毛藻骨架目标的距离求解过程。实验验证算法的可行性,结果表明该算法可以获取与角毛藻形状拓扑一致的特征。     

基于GIS黄河口拦门沙区域水深线的自动提取

为了能够实现黄河口拦门沙区域水深线的自动提取,结合ArcGIS Engine分析了水深线提取的步骤和给出了程序实现的关键代码,实现了黄河口拦门沙区域水深线的自动提取,并成功应用于黄河口地理信息系统。     

基于变分水平集方法的海冰信息自动提取

针对目前海冰信息解译时对海冰外缘线及面积信息提取不精确、业务化应用不强问题,提出一种基于分裂Bregman算法的海冰外缘线自动提取方法,并通过遥感影像预处理、算法程序化等工作步骤,将该算法应用到业务化海冰信息解译工作中。方法:分别选取五景中、高空间分辨率的可见光卫星遥感影像,将影像上待提取海冰区域首先进行不规则图像裁剪、图像增强等预处理工作,然后基于变分水平集及快速分裂Bregman投影方法进行了海冰外缘线信息的提取,并对提取出的海冰面积进行量化,最后与传统人工提取海冰信息进行了比较。实验结果表明,基于变分水平集及其快速分裂Bregman算法提取的海冰信息,具有提取的海冰边缘精确、自动化程度高、提取结果稳定可靠等优点。     

安全管道判断算法及其优化

结合射线法和环绕计数法的优点,提出了有向穿越计数算法,该算法更加高效且容易实现,可作为安全管道判断的首选方法。对3种特定类型的安全管道进行了有针对性的优化,其中单调多边形管道的时间复杂度提升到了O(log n)级别;通过建立基于概率分布的简单外部或内部边界,在绝大多数情况下只需一次判断,优化了平均时间复杂度;通过改变顶点排列顺序,将有向穿越计数算法扩展到环形管道。     

大亚湾风暴潮波浪传播数学模型

本文建立了大亚湾风暴潮涌浪传播数学模型,以任意多边形离散计算海区,每一多边形构成单元,以波浪运动学和动力学守恒方程模拟单元内能量传递,以风暴潮过程模拟边界入射波高过程,用风暴潮涌浪传播基本方程和波能缓坡方程结合模拟湾口巨浪向湾内的传播过程。通过分析大亚湾不同种类岸线反射系数的概率分布,并结合实测波高对模型进行率定,最终确定模型参数。将大亚湾特征点计算波高与统计推荐波高比较进行模型验证,结果显示SE向波高与H_(13%)推荐波高对应较好,可以用于大亚湾海区的波浪预报。计算当大亚湾口分别出现10年一遇、50年一遇及100年一遇的波高时,在E、ESE以及ES向入射波浪条件下大亚湾海域极值波高的分布。分别对风暴潮涌浪在不同类型岸线的爬高以及风暴潮涌浪传播对岸线的作用力进行计算。     

An algorithm of image processing for underwater range finding by active triangulation

In this paper, we present an algorithm for range image processing to reduce effects of underwater environments on the quality of range finding. This algorithm of image processing is based on the principle of the least-squares error method, which fits discrete image data to continuous piecewise curves. To simply the fitting of image data, the interval of each row and column is subdivided into several subintervals. Then a straight line is used to fit the image data within the subinterval. To merge two adjacent lines together, a weighting technique with a linear weighting factor is imposed. After the image is processed, it will provide a better imaging quality than the original one if values of the design parameters are properly assigned. Thus, a series of design of experiment process runs are carried out to study effects of the design parameters on quality of range finding. To make the proposed algorithm robust against noises, both environmental illumination and turbidity are forced into the experiments by utilizing an outer array. From the results of the range finding experiments, it was found that the proposed algorithm of image processing in truth has potential of increasing quality of range finding. The results also show that the proposed algorithm can achieve high quality of range finding only having the processing of row elements. Also, the quality of range finding by using the proposed algorithm of image processing is superior to that of using a bandpass optical filter.     

一种基于Voronoi多边形的海底底质表示方法

海底底质对舰船航行、锚泊、登陆、铺设海底管线等海上活动具有重要的影响。文中提出了一种基于同质Voronoi多边形的海底底质分布可视化方法。通过构建Delaunay三角网,求取Voronoi多边形顶点,并依次排序顶点,从而生成构成Voronoi图。在Voronoi图的基础上,提出了同底质Voronoi多边形合并的具体算法,并处理与岸线相交的区域。实验表明,文中所提方法对于海底底质分布的可视化表达,比传统方法更为形象、直观。     

绝对精度自动匹配的图斑椭球面积解算方法

针对传统模拟积分法的图斑椭球面积误差模型构造复杂及绝对精度无法自动匹配问题,以梯形图幅面积理论计算公式为关联纽带,采用纬线等分割补的手段构建了梯形图块面积的通用计算公式.在分析梯形图块面积替代误差数值分布规律的基础上,通过纬度积分步长变量的引入建立了严密的面积替代误差数列模型;阐明了纬度积分步长变量调控下面积替代误差数...     

Using the adaptive simulated annealing algorithm to estimate ocean-bottom geoacoustic properties from measured and synthetic transmission loss data

This paper presents the results obtained using the adaptive simulated annealing (ASA) algorithm to invert the test cases from the Geoacoustic Inversion Techniques Workshop held in May 2001. The ASA algorithm was chosen for use in our inversion software for its speed and robustness when searching the geoacoustic parameter solution space to minimize the difference between the observed and the modeled transmission loss (TL). Earlier work has shown that the ASA algorithm is approximately 15 times faster than a modified Boltzmann annealing algorithm, used in prior versions of our TL inversion software, with comparable fits to the measured data. Results are shown for the synthetic test cases, 0 through 3, and for the measured data cases, 4 and 5. The inversion results from the synthetic test cases showed that subtle differences between range-dependent acoustic model version 1.5, used to generate the test cases, and parabolic equation (PE) 5.0, used as the propagation loss model for the inversion, were significant enough to result in the inversion algorithm finding a geoacoustic environment that produced a better match to the synthetic data than the true environment. The measured data cases resulted in better fits using ASTRAL automated signal excess prediction system TL 5.0 than using the more sophisticated PE 5.0 as a result of the inherent range averaging present in the ASTRAL 5.0 predictions.     

Increasing underwater vehicle autonomy by reducing energy consumption

In this paper, we concern ourselves with finding a control strategy that minimizes energy consumption along a trajectory connecting two given configurations. We develop an algorithm, based on our previous work with the time optimal problem, which provides implementable control strategies that are energy efficient. We find an interesting correlation between the duration of these trajectories and the optimal duration. We present the algorithm, control strategy and experimental results from our test-bed vehicle.